Alcohol consumption shown to reduce brain size, similar to sped-up aging
The effects of alcohol consumption have been controversial: studies over the years suggest alcohol consumption reduces inflammation and is able to flush toxins from the brain but also stunts brain growth and causes early-onset dementia. A new meta-analysis of more than 36,000 MRI brain scans by researchers from the University of Pennsylvania (UPenn), however, reveal even modest alcohol consumption causes structural damage and compound brain volume loss over time – people that drank four or more units of alcohol a day showed brain volume loss equivalent to a whopping 10 years of aging.
The team at UPenn sourced data from the UK Biobank which hosts high-quality MRI brain scans from nearly half a million British adults of varying ages. The study focused on self-reported alcohol intake of chronic heavy drinkers e.g., women that take three or more drinks daily, and men that take four or more. (The National Institute on Alcohol Abuse and Alcoholism, US, recommends that women consume an average of no more than one drink per day; recommended limits for men are twice that.)
The findings came as a surprise as just one to two units of alcohol a day reduced overall brain volume and gray matter volumes across several areas, as well as microstructures in the white matter. For reference, a pint or can of beer or cider, or a standard glass of wine, represents two units.
UPenn researchers also noticed that this effect was not linear across the dataset: going from one daily unit to two (half a beer to a glass of wine) was roughly equivalent to two years of aging; going from two daily units to three (a glass of wine to one and a half) was like aging three and a half years; and drinking four units of alcohol a day – two beers, or two glasses of wine – was equivalent to a full 10 years of aging
“There is some evidence that the effect of drinking on the brain is exponential,” said former UPenn postdoctoral student Remi Daviet, now an assistant professor of marketing in the Wisconsin School of Business at the University of Wisconsin-Madison. “One additional drink in a day could have more of an impact than any of the previous drinks that day. That means that cutting back on that final drink of the night might have a big effect in terms of brain aging.”
The researchers hope to delve into additional questions related to alcohol use in future works. “This study looked at average consumption, but we’re curious whether drinking one beer a day is better than drinking none during the week and then seven on the weekend,” said assistant professor Gideon Nave, from Penn’s Wharton School Department of Marketing. “There’s some evidence that binge drinking is worse for the brain, but we haven’t looked closely at that yet.”
“[But] we may be able to look at these effects over time and, along with genetics, tease apart causal relationships,” Nave added.
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